The present invention relates to apparatus for feeding documents from a stack or pile one-by-one into a document path for further processing. The present application particularly relates to, but is not restricted to, document and check sorting equipment.
In document and check sorting equipment it is known in the art to provide a stack or pile or documents as an input to a machine. Documents are drawn from the bottom of the stack or pile by a wheel assembly which is urged against a face of the document which is at the bottom of the stack or pile. The pressure of the pile against the wheel causes the document to be moved sideways from the bottom of the stack or pile to be introduced into and moved along a document processing path. The necessity that the document be moved by friction against a wheel means that considerable pressure must be applied to the stack or pile. This is not beneficial in that it raises the amount of force required to move the document from the bottom of the stack. Similarly, should the co-efficient of friction of the wheel against the lowest document prove to be less than the co-efficient of the document against the document next there-above, two documents are fed from the bottom of the stack and can cause malfunction of the document path wherein the two documents are introduced. The present invention seeks to provide a document feeding apparatus where only light pressure is exerted upon the stack sufficient to cause the stack to reach the bottom of an input hopper and wherein the feeding of individual documents is not dependent upon co-efficients of friction responding to the overall pressure of the stack.
The present invention consists of an apparatus for feeding individual documents in a first, preferred direction from the base of a plural stack of documents, said apparatus comprising; a pneumatic suction head operative to grasp a face of a document at the base of the stack when air is induced to enter therein; motive means, coupled to move said head in a first stroke in a second direction opposite to said first direction, and thereafter in a second stroke in said first direction; and a pneumatic vacuum source operative to induce passage of air into said suction head during said second stroke.
Pneumatic vacuum sources as known in the prior art are bulky and expensive and require repeated maintenance. The present invention in its preferred embodiments seeks to improve over prior art vacuum sources by providing that the vacuum source comprises a reciprocal air pump coupled to the motive means to operative in synchronism with movement of the suction head.
Provision of sufficient instant energy to create a standing vacuum through a suction head of any great value necessitates the provision of large instantaneous power. It is known in the art to provide such power by means of large motors. The preferred embodiment of the present invention seeks improvement over the prior art in this respect by arranging that the motive means comprises an elastic potential energy store operative to store potential energy during the first stroke and to release that potential energy during the second or return stroke. The preferred embodiment of the present invention also provides that the first stroke is achieved using less power than the second stroke. In this manner a low power motor can be used to store potential energy which is suddenly released in a high-power burst on the second stroke.
In order that the second stroke may be initiated the embodiment of the present invention provides a retention means for retaining the motive means at the termination of the first stroke which is then selectively operable to initiate the second stroke. In one preferred embodiment the release means is a solenoid engaging a recess on a shaft, the solenoid being selectively operable. In another preferred embodiment the release means is a cam and cam follower on a motor where rotation of the motor beyond a first angular position (where it is retained at the end of the first stroke) causes the cam follower to have virtual freedom of movement for the return or second stroke.
While it is known in the art to provide air pumps in the form of fans or blowers, the embodiments of the present invention seeks simplification over the prior art by providing in one embodiment that the reciprocal air pump is an ordinary barrel air pump and in another embodiment that the reciprocal air pump is a bellows. In each instance, in order that a document shall be released into the document path, the embodiments provide that a release valve is engaged at termination of the second stroke to release any residual vacuum in the reciprocal air pump. In an alternative embodiment it is arranged that the air pump is leaky so that the vacuum is self-releasing after the suction head has moved sufficiently far to cause the document to be introduced into a subsequent document track.
In the embodiments of the present invention it is provided in one instance that the energy store comprises a spring, and in another instance that the energy store comprises a mass of air which may either by compressed or rarefied as a result of the first stroke and whose stored potential energy is converted into kinetic energy on the second stroke.